Solar collectors are known in the art. Example solar collectors are disclosed in U.S. Pat. Nos. 6,050,526, 5,347,402, 4,572,160, 4,056,313, 4,117,682, 4,608,964, 4,059,094, 4,161,942, 5,275,149, 5,195,503 and 4,237,864, the disclosures of which are hereby incorporated herein by reference. See also U.S. Publication Nos. 2007/0223096 and 2009/0101208, which are also incorporated herein by reference.
A component in a Fresnel mirror concentrated solar power generating plant is a secondary reflector mirror assembly. The mirror in the secondary assembly, called the secondary reflector panel (or SRP) is bent or formed, typically from an aluminum sheet. Conventional SRPs, when installed as part of the secondary reflector assembly, often experience problems (e.g., do not function or are otherwise limited) when a maximum operating temperature of about 270 degrees C. is met or exceeded. For instance, as temperatures generated by the panel exceed 270 degrees C., the formed aluminum panel becomes altered in its physical material characteristics. These changes degrade the solar reflective performance of the aluminum surface and prevent the generated temperatures from exceeding about 270 degrees C. in the SRP assembly unit.
In a CSP plant, a secondary reflector panel typically helps heat an absorber tube that is filled with water or other heating fluid. The water is converted into steam with a temperature of about 270 degrees C. and a pressure of 55 bar. The steam is used to drive a turbine-generator unit, thereby producing electrical power. The overall efficiency of the Fresnel reflector solar power generating system thus is tied to the temperature and pressure of the produced steam. Increasing the solar reflectance generated by the secondary mirror panel and increasing the operating temperature of the panel increases the energy input to the steam. This directly increases the power and thermal efficiency of the Fresnel power plant. This efficiency limitation is a driver for the competitiveness of this technology versus other solar thermal technologies such as parabolic trough and central receivers.
Thus, it will be appreciated that there exists a need in the art for improved secondary reflector panel or the like.
In certain example embodiments, there is provided a method of making a secondary reflector panel. A reflective multi-layer coating is disposed on a major surface of a glass substrate. A portion of the reflective multi-layer coating proximate to edges of the glass substrate is removed. A frit material is disposed over the glass substrate including both the edges thereof and over the reflective multi-layer coating disposed on the glass substrate. The glass substrate, as well as the reflective multi-layer and the frit material disposed on the glass substrate, are heated to an elevated temperature so as to cure the frit material. The glass substrate with the reflective multi-layer and the frit material disposed thereon is bent during said heating.
In certain example embodiments, there is provided a method of making a secondary reflector panel. A silver-inclusive reflective coating is disposed on a major surface of a glass substrate. A frit material is disposed over at least a portion of the reflective multi-layer coating. The substrate, with the reflective coating and the frit material thereon, is heated to a first elevated temperature to dry the frit material and remove at least some of solvent from the frit material. The substrate, with the reflective coating and the frit material thereon, is bent while a second elevated temperature is applied thereto. The fit material is cured during application of the second elevated temperature, and the second elevated temperature is higher than the first elevated temperature. Following application of the second elevated temperature, the reflective coating is substantially hermetically sealed between the frit material and the glass substrate.
In certain example embodiments, a secondary reflector panel is provided. A heat treatable low-iron glass substrate has a thickness of about 1.6-3.0 mm. A multi-layer reflective coating is disposed on the low-iron glass substrate, with the multi-layer reflective coating including at least one layer of silver sandwiched by first and second layers including Ni and/or Cr. A ceramic fit material is bonded to at least a portion of the multi-layer reflective coating and further bonded to at least a peripheral portion of the glass substrate where the multi-layer reflective coating is not disposed. The ceramic frit material at least initially includes a non-water carrier system. The secondary reflector panel has a total solar reflectance of at least 93%.
These features, aspects, and advantages may be used in any suitable combination or sub-combination in different embodiments of this invention.